Write back to where the notice was issued with a copy of GC. - 回

Although you may simply ignore the notice, while it is not a practice that USCIS issues such notice to everyone who becomes OOS, for just several months.

So I guess there should have something on your side got their attention.

Doing what I suggested above may save you trouble later, say what if you are caught by ICE and have no chance to bail before seeing a judge?