advise on boyfriend messaging his ex girlfriend

Ok so I don't no if I'm just being a paranoid pregnant mess or if it really is something I should question...me and my partner are trying to move house and the other day he said an 'old friend' messaged him with some advice about it all...then a few days later I over heard him telling his mum that it was his ex girlfriend who messaged him the advice. so just to see what he would say I asked him to message his 'friend' again to see if she has anymore advise...he wasn't so keen so didn't but last night when I was working he text me saying he had messaged her again...(Why was he only keen to message her when I was at work?) anyway...he still hasn't told me it's actually his ex girlfriend and he doesn't know that I know who she is...would you be worried?