Rising damp?

[flosswoss]

When I look at the back of my house from a few feet away there's a bit in the corner that looks 'different' - slightly darker. It starts at ground level and is about 2-3 feet high. It doesn't feel damp (would it?) and there's no obvious patch on the inside. There isn't a leaking drainpipe or anything above it. There is a damp proof course but I understand this can fail sometimes. I've arranged for an expert in such things to have a look but have to pay �60 for this inspection. Do you think I'm worrying over nothing or being prudent? Thanx