Generally no, same with Facebook and the likes.
I've had the opportunity as well, as mine often leaves her phone lying around, or askes me to shove it in a pocket when dancing and has left the FB password from when she uses it on my phone (bigger screen) but I don't do facebook and don't go there unless she wants me to have a laugh at something someone posted.
Otherwise, keep your own phone tidy (save other messages off in a text file maybe
) and never have a problem about letting her look through it.