One of my batteries was involved in an automobile crash three years ago and came out of it with a crack or two in the plastic casing. I have been flying it ever since with no problems at all. I suggest you keep your eye on them. If the battery eventually goes weird somehow, chuck it at a battery recycle place such as Best Buy.
Yes, I have hairline cracks in the area of the LEDs on both of my batteries. Initially, a year ago I noticed the cracks on one battery but then the cracks appeared on the other one too. The plastic in the area of the cracks appears to be slightly raised as though there has been pressure from the inside. I wondered whether this was caused by the batteries going into the programmed slow discharge while inside the foam case. When I open the drone case as the batteries are discharging I can sense that it is slightly warm but the batteries certainly do not feel hot. My batteries both seem to be operating perfectly so I haven't been unduly concerned.
I suspect that it would be more sensible to store the batteries at 50% charged and then charge to 100% before setting off to fly. However, I so rarely get decent flying weather that I recharge the batteries straight away in the vain hope that another opportunity to fly might present itself in the following days.