Apraxia Moms

Good morning! I have another question for you ladies today. Do Apraxic children generally have high tone in the lips, tongue, etc that interferes with the way that they use their oral structures? My son does the thing where he grasps for words, but his SLPs have always said that his main problem is that he has such high tone around the mouth that it is interfering with how he is able to use it. Like, so high that it is hard to get a tooth brush into his mouth. This is the only area that has high tone, the rest of his body is low.
His SLPs focus on a ton of lip rounding and stretching exercises and prefer to do OT first, because they say it really helps him to relax out of the retracted position he tends to stay in. I am just wondering if this is a common characteristic of Apraxia, or something else? I am having trouble finding references to this in the Apraxia literature I have been reading.

Just to clarify, he does have an apraxia dx. He has worked with 3 different SLPs at the same therapy center and they are all saying the same thing.