We like to err on the side of caution with mirrors, because many people read these threads (including brand new owners). Itís very common for them to cause problems for budgies.
If there is no problem for your birds at this time then fine. Make sure to monitor your birds closely with the mirror toy. Mine have a small plastic pear with a hole in it for them to stick their head in and look in a small mirror inside it. They do so occasionally with no issue.
I used to have a ladder with a mirror which came as a set with other toys, so I put it in and decided to monitor my birds use of it. For a while it was fine, and largely ignored, but one day I started noticing smudge marks on it when Chip started getting a little too interested in it and began to feed it. I then removed it.