I know everyone says BH's aren't supposed to be painful, but I find that mine are pretty damn uncomfortable. I get an ache in back and belly and feel everything tightening - it's very different to labour contractions though, not the same sharp pain but certainly not "painless" either.
I had them with my DD and have found them worse with this pregnancy. I think they tend to get stronger with every pregnancy you have.
Try drinking some more water (dehydration makes them worse) and taking it easy - sounds like you were out and about today - but if it doesn't help and you're still feeling uneasy by all means I would go get checked. But it does sound more like BH to me?
good luck.