I was just checking my rear tyres and using just my thumb to gently
press against the tyres an unusual squeeking/creeking sound (coming from the rear suspension I think...) can be heard?

This doesn't happen for the front tyres. But, what got me concerned is that
I don't need to exert any force at all on the rear wheels to get this funny
creeking.

Can anyone say that this is a problem?

Cheers!