A 7% drop in battery health over four months is a bit on the high end. Typically, iPhone batteries will lose 1%-2% a month under what is considered "normal use". Seeing a 7% drop in a short amount of time could indicate that your battery is degrading faster than normal. With that said, there are many variables that impact battery health such as usage, charge cycles on the battery, and the environment you live in.
You can visit an Apple Store for them to do a diagnostic check, but they will probably tell you the same thing.
I would not worry about it.
See here for more info: iPhone Battery and Performance - Apple Support