Water leak

Saturday, there was a small puddle of water under and around the front loader Samsung washing machine. Washer is up on a wall, and on other side is concrete front patio. Water puddled under the washer and dryer, and also ran under the wall onto the patio. I could feel water all along the lip under the front of the washer, so it being 8 years old, figured it was time for a new washer. We got a LG front loader Sunday and I installed it, having done it before and had no issues.

Wife ran a 20 minute load and was fine. She started a second load of 1:20 minutes and it started the same kind of leak, also leaking under wall to the front of house. It was pretty much the same scenario as on Saturday with the old washer. So we called a plumber on Monday and today was earliest one could show. He started a load in washer and short cycled it so he could here it drain. Didn't seem to think the drain pipe was cracked or leaking, and could hear water rising in drain pipe and dropping with a whoosh. So he snaked the main line, as the washer drain line ran into it. All seemed to be ok after he kept short cycling the washer to hear the water in the drain pipe.

He left and I ran a 2:00 load, probably more stuffed in it than I should have since it was piling up after 3 days, figuring that was best to see if any more water would show up. I kept checking it with a flashlight every 15 minutes and all was fine. Once it had stopped, I noticed a small amount of water leading from under the washer into the gap between the two machines. It was maybe a couple of tablespoons full of water, and nowhere near the large amount from Sunday. I wiped it up and ran a 20 minute load and all was fine, no water.

What's going on here, and where is the water coming from. All connections look good. The floor is concrete with linoleum flooring, no seams in it.

I'm in Texas, south of DFW and yes, we had a hard freeze a week ago. No lines frozen as they are all wrapped and covered.