Welp, first you were spotted so they had an idea of where you were going, then you actually decided to fuze a window where enemies might be near or within hearing range without droning the area.
That loud placement of fuze is a dead giveaway and an easy wallbang if people are listening correctly. He wasn't hacking at all.
He could of been placing it on objective of window for all you know so how did he know? If you actually look when he died it was just before he placed it. The sound came up and he was instantly dead.
He did get spotted but that doesnt mean he saw where he was going .
I would call suspicious but in my opinion he saw you and decided to destroy that window while you where placing it
If he was cheating he would of shot above the X but near the center sense thats where your head would be.