Not exactly a bug, but this feature appeared a few months ago.

When first visiting delta.com, the "focus" field is "from airport". This automatically places your cursor in the "from airport" field. The problem is the focus doesn't move the cursor until most other content on the page has loaded. Assuming you are starting from a blank web page, when you visit delta.com for the purpose of logging into your account, you can click into the PIN field and start to enter your PIN but as the page continues to load the focus changes to "from airport" and you end up typing your PIN into "from airport".

I realize I can simply visit delta.com and wait a few seconds to click into the PIN field to enter my PIN, but on a wireless aircard or lousy hotel internet circuit it takes a while to load other content and for the focus to change to "from airport". I don't know if older versions of the home page did not have a focus or if current code just causes the focus to take effect late in the page load, but for those that don't visit delta.com to buy a ticket from the home page, it is a PITA.

I usually log into my account before I search for flights or do anything else so that it recognizes my Medallion status. Lately I end up entering my PIN in the "from airport" field almost every time I visit delta.com.