Heard 3 knocks on door at 3am what does it mean?

Last august 20th at exactly 3am, I hears 3 distinct knocks on my bedroom door. The wife sleeping next to me heard nothing. This scarred the heck out of me.. 4 days later my sick uncle died. 10 days ago, I distinctly heard 2 knocks on the door at precisely 3am,,Any idea what might occur next?