If she is happy and drinking okay, then I wouldn't worry too much. A temperature above 38 degrees is almost never due to environmental factors - it is much more likely to be either a result of teething, or perhaps a viral infection.

There is no need to worry about bringing a temperature down. It is an important sign that guides us to how our children are coping with an illness, and the temperature itself won't hurt her. Masking the temperature with paracetamol or ibuprofen might makes us not be as worried about an illness as we should be, though, so for that reason I recommend not using paracetamol unless it is really obvious they have aches and pains - grizzling and crying, for instance.