My first reaction in "no". But they might be..... At some point in the past (not sure if it was 50 years or 100 years) the BEP stopped allowing anyone ot have uncut sheets. For many years the Sec of the Traes and Treasurer were presented with an uncut sheet, but even they were cut off and only given a sheet that had been cut up and re-assembled. 1928 may have been before the "new" policy (outdated now) was implemented. If they do exist, they will be quite rare and expensive.
MJC; Legal Tender $2's were available in 12 subject sheets. They are actually plentiful and priced from around $600 to $1500. There were 8 issues of the 1928 series and the scarcest issue 1928B, uncut sheet is worth over $7,000. The best possible place to locate an uncut sheet would be the Paper Money show in Memphis next month. See you there!