Can you explain this inconsistent behavior with date import?

Question

You have to be able to connect to an oracle database with the package ROracle to run this example.

I cannot explain this behavior:

library(ROracle)

## Here you have to set up your connection with details I cannot provide
conn <- dbConnect(dbDriver("Oracle", dbname = "xxxxxx")

query <- ("select to_date('03/28/2019', 'MM/DD/YYYY') as D from dual")

rs <- dbSendQuery(conn, query)

fetch(rs)

And this the result I got:

                     D
1 2019-03-27  23:00:00

Ok we are almost there, just have to wait for an extra hour but what is happening here?