Weird Ex scenario - Needs your opinion!

[Le Chat]

I went out with and was engaged (for 3 yrs) to a bloke..the relationship was from 1991-1994. I have since been married twice since then and am very happily married to Mr Le Chat with 2 children.
Last December I went to a funeral of a lovely guy, who was only 36 and the mutual friend of both myself and the ex from my first paragraph, whose name is Alan. After the funeral and before the wake (which I was not able to attend) Alan came back with me to my place of work, as it was really close to the church and had a coffee. We didn't part on really bad terms but it was me who terminated the relationship, as I just really didn't particularly like or fancy him anymore.
We chatted and had a pleasant exchange and a bit of a giggle. Himself and his partner were due to have a baby...I wished him well and off he went.
Now, last week, in town, I was with my 2 boys and he approached pushing a pram, with his partner. He looked at me and was going to walk straight past with just a nod to say 'hi' but I stopped for a peek at the little 'un.
It was so awkward, he hardly spoke and after I had had a bit of a gush about the cuteness of the baby, it was just really tense. He wasn't going to introduce me to his partner, until I purposefully looked at her and said "hello!"
I started waffling and then just said "Well, it's lovely to see you again.." and then I left.
My question is this....Why was he so friendly and 'normal' in the December, when he was on his own and why was he so uncomfortable when I met him the other day. Surely, it can't be because his partner was with him and he acts differently? I am perplexed and curious to know what you guys think!!

[Doc Spock]

Like any chap he would be bothered with what his current wife would say. You women are a funny lot you know, I am on 3rd wife and still don't understand women.

Sounds like normal behaviour to me, don't worry about it. Most people talk more freely when partner isn't with them.

[bednobs]

why couldnt it be because the partner was with him? Perhaps the partner is a harridan, who dosent allow him to talk to other women? perhaps she has just discovered he had an affair, and so talking to any kind of ex would be a big no-no. perhaps they had had a row? perhaps he had just found out his mother has cancer?
i wholeheartedly agree with doc spock (wow!) and think you are reading too much into it

[4getmenot]

probably was because of the partner but you happily married, I really dont see why you need to know.

[Whickerman]

Actually, I think he was incredibly rude. And if he can't bring himself to say hello just because you had a fling 13 years ago (before he met her?) then he's also immature. And if it's down to her, he deserves her if he's willing to put up with it.
And even in that case, he could've introduced you as 'an old friend'.

[Le Chat]

Doc Spock - I thought this was the most likely reason!
bednobs and 4get - Although I may appear to be reading too much into it, I am just really genuinely interested into your opinions as to why he was so different. If I'd met him, or any other ex,( including my ex husband,) whilst out, then I would be exactly the same whether I was on my own or with my husband. I suppose that I expect other people to be the same generally ...not adapt or change how they act depending on who they are with at the time!!
whickerman - He was really rude and it is so ridiculous as it was 13 yrs ago that we were together and yes, we were both single then.

[fruitsalad]

something similar use to happen to me, a guy i use to speak to and pass the time of day with,( never dated him or anything, ) when i was on my own he would chat or say hello if i was with my husband he would just walk by, and not say a word. in the end i stopped speaking to him at anytime. if he could'nt speak when i was with hubby i did'nt see why i should speak when i was alone.