This happened to me with our March flights. The times shifted 25 minutes, not a big deal, but the EB never showed up, even though I had purchased it. I had to call them so they could correct the problem.
The only problem I had when Southwest changed my flights was that it then prevented me from making any changes online. I had to call and rebook every time the points needed went down. I also ended up with an EBCI problem. They used my return EBCI on my outbound flight, so when I checked in to come home, I was B56 because it no longer had a valid EBCI. My DD and DH still had A23 & A24 so they boarded and saved me a seat. I had to call a special customer service # after I got home to get the $12.50 refunded.