I'd consider it an abnormally long time to not poop, but due to my recent similar experience, i'd say it a can be nothing. But our situations may differ, so you might want to check the belly for any hard lumps.
Mine went 3 months without poop despite twice a week feeding, so i was starting to worry. A day after i post my problem she proved i was a silly worry wart by leaving me a huge present, roughly a third of her body length.