False reading??

My LO woke up kinda screaming her head off differently than usual so after changing her diaper I took her temp which came out to 99.7(thermometer is the forehead device). She was hungry so I fed her and she ate her normal 4oz. No fuss or anything after eating she fell right asleep. I took her temp again and one says 98.7 and the other was 99.0. Should I just call the nurses line to get their opinion or assume the first reading was off since she was just waking up and crying or should I be rushing to the ER. She just turned a month old.