My girlfriend has a problem?

me and my girlfriend just started having s*x and we did it without condoms but pulled out (no worries shes not pregnant) and we did it with condoms, I have never had sex before and she has but only with two other guys. But when we where having sex with a condom I pulled out and there was something on the condom that looked like sem*en but it wasn't. She said that she has an allergic reaction to the latex or something and thats what it is from. She said she doesn't have any STD's but could it really be from a reaction to the lube or condom?