It's absolutely fine. We're human and we experience more than one emotion, you can have an off day, you can think contradicting thoughts every now and then what's important is you don't give these situations any power. After all, what you resist persists. 

Like Stacey said don't give it any power at all , it's very difficult to not think any Negative thoughts through the day but just think of somthing different that feels better to you, the circumstance or the thought don't matter it's your state of being that matters, just use a different thought that feels better, then that will change your state of being