There are numerous data errors involving Open and Low for WBA. For example, see May 28, 2013, Jan 20, 2009, Nov 28, 2008, Sept 5, 2006 and many more like these.
Thanks for the data error report @olesmithy I have confirmed the errors and submitted a ticket to engineering for correction.
Good catch @rayo I did a search and found the previous ticket which is still open and have merged them together now.
This date should now be correct on our site. Thank you.
The bad O(pen) and L(ow) prices in Historical Data for WBA still exists. The funny thing is when you display a range of dates the data is bad but when you place a bad date in the Start Date of the Time Period the correct prices appear. That shouldn't be possible. The data is there or it isn't, it can't both be there and not be there.