Stress can make them worse, that is for sure - especially considering what you have been and are going through.
Also, postural changes bring on PVCs and palpitations also. I get them a lot when I bend down quickly or get up quickly - or when I get up, use the bathroom and lay back down just like you did.
Everytime I get up, I sit up in my bed for about 30 seconds to give my body a chance to adjust, then stand up fairly slowly. I started doing this after I almost vomitted and got PVCs when going to the bathroom.
Also, you didn't mention if you had a cardiologist check you out - have you, yet? If not, I suggest getting a full work-up, mostly to ease your mind :)
Sorry to hear about your mother and your uncle. It sounds like you are going through high anxiety right now, and that could very well be the cause of your palps. Stress can do all kinds of nutty things to folks. Also, this time of year, being the holiday season and such, can have a bearing as this is your first year without your mother and it is sad. I know, my beloved mother died 2 years ago, and I STILL get very sad over it, we were best friends.
Anyway, try not to stress too much, and if they really get worse and you just can not stop worrying, see your doc, he or she, will be able to put your mind at ease. I am sure they will tell you the same thing, STRESS is at the bottom of this.
God bless.
Susie