Absolutely fine. I had dreadful trouble finding a non-pink pram and non-pink doll for my ds. I eventually found a red toy stroller and my ds loved it - still does at nearly 7 years old. He's probably going to be a Dad one day, why not play at being one now?
It is funny though to see how my ds & dd played very differently with dolls/prams/etc though. When my ds and my nephew were around 2 they would put each other in the toy pram and push each other into walls and they thought it was hilarious! Basically running fast with the pram and bashing it into things was the aim of their play, together or alone. Whereas my dd carefully puts her doll in the toy pram, tucks it in and carefully pushes it around.
Boys & girls are different, but toys need not be gender specific.