I am not an expert, but I think you should be alright to use a 100W amp with 50W speakers. I don't understand the science of it all, but to give another example, I know that you can get power amplifiers rated at 600 Watts per channel - far greater than most speakers.
I think that problems are most likely to occur when an amplifier is underpowered.
I would guess that your speakers would only really be in danger if you cranked the volume up towards the maximum.
However like I said, I am not an expert so it might be safer to wait for someone more knowledgeable to confirm this!
As I said, should be ok. The actual output of a 3802 is around 85 watts per channel (all channels driven), despite the claimed 105/110. Most problems are caused when the amplifier is not powerful enough and can´t provide enough grunt to the speaker, causing the amplifier to clip, this produces distortion and usually fries the tweeters.
If you wound it up to maximum volume for hours on end you may eventually blow a driver in the speaker but for most people this isn´t likely to be the case, unless you like your music/movies at max volume!