Patents assigned to former employer

I have about 10 patents applications filed when I was with my former employer. I left the company after being there for 2 years on good term. Now most of the patents filed (I am the invenotr or a co-inventor) have been granted. The company provides $2000 bonus for each inventor per granted patent to its active employees. I am not with the company any more, so I was given nothing. Now the company is sending me several letters to ask me to assign the patent to the company "with one dallor and other significant considerations". Th letter used the following words "with one dallor and other significant considerations" so I assign the patents to the company, which I saw nothing else but a selfaddressed letter. What I should do? Just sign and send back? Can I ask for anything (like the $2000 /per patent they award to employee)? Thanks.

_(b) _(u) _:'(