Ok please tell me if you think this is messed up?

ok my gf is almost always busy and its hard to see her alot. so this week she said well hang out on the weekend. ok well saturday she wasn't feeling very good ok so i said ok ill leave her alone i wanted to come over to just be near her maybe help her with her cold. but i said fine ill leave you alone. ok so the next day i get a call at 9 in the morning unfortunately i was asleep and didn't wake up till 10. i woke up and checked my phone she said call me back. so i said ok i called her cell she didn't answer a few hours ped and still no answer. finally 5 o'clock comes around and my friend sammy calls me and said hey whats up i simply said hey how are you she said i had so much fun today i went with kierstin to the movies...kierstin is my gf i got pissed she could have told me that she was going out i mean come on i gave her the day to rest and the next day she goes out doesn't tell me shes going anywhere so my question is was it rude of her to do that or am i over reacting?