I guess she could have said it in a nicer way... e.g. "Excuse me, are you okay in there? You've been awhile") though 4 mins isn't that long, if you are a woman especially, us girls know these things take time
Unless, as SydEY mentioned, she saw another go in.... hey.... maybe she saw a girl/guy (circle which applies) go in before you, and didn't see 'em come out, and then saw you go in....
Sorry. But we all know that's what they think!
Once I had an F/A check on me because it got quite bumpy while I was using the lav, unbenownst to me the door hadn't latched properly, so when she knocked on the door it came open!
Thank goodness I'd done my thing and was wiping the sink, as there was rather a lot of blokes standing around waiting!
Sky