Almost all other strings in dom.properties use the form "Use of X is deprecated. Please use Y intead". These two strings should probably use the same structure for consistency (that's what I'll do in my locale, but I thought it was worth mentioning here).
Feel free to file and fix (or just tag with, um, whatever the good first bug notation is these days) if you want. The existing messages are perfectly understandable, tho, and nearly the format you note anyway, so it doesn't seem quite important enough for me to take time to fix (or rather, to do instead of other work I could be doing).