I think i seen this girl i'm talking to with another guy?

Its not that big of a deal but i really like this girl. Shes already lied to me once about freaking face book. WOW yea i know who care about face book it wasn't a big deal but she said she never gets on it.. Well i logged on to my friends account and found out that she posts every day. " Blake is coming over. going riding with Rodney. now i knew about Rodney. I had no idea this guy named Blake was going over to her house. She said she told him about me. But back to the main problem. She said she went fishing with her dad yesterday which is fine i don't care.. but she said she got burnt. Well i went out with some friends to the movies and as we were leave i noticed this lady that looked so so so familiar curly blonde hair nice tan. I had a GUT feeling it was her. i watch her pretty closely, well as she was getting into the guys car she put her head down. i looked and looked, as they drove off she would just look away but to me it seemed like it was her and didn't want to be seen.... Then today she has to go to the doctor for a check-up. well after that she text me like 2 hours later and said sorry just getting out of the tanning bed. i reply "i thought you were burnt" 10 mins later she said " i am tan now" .. i don't know. i just feel weird. if i ask she will either get mad and say you don't trust me and i don't. I did but i don't now. But i know that it will come back if she don't lie. something just seems off here to me. any help?